Some conventional vehicles include all-wheel-drive capabilities. These vehicles power two wheels during high-traction situations to enhance fuel-economy, and power all four wheels during reduced-traction situations to enhance road traction and stability. Torque-biasing devices are conventionally used to transfer the torque output from the engine source away from a first wheel and towards a second wheel during the reduced-traction situation.
During a reduced-traction situation, one of the wheels of the vehicle often has a much faster rotational speed than another wheel. Torque-biasing devices are conventionally controlled based upon the difference between the rotational speeds of a first wheel and a second wheel. Once the torque-biasing device is activated, the vehicle powers all four wheels and the effect of the reduced-traction situation is hopefully minimized.
A problem arises, however, during a tight turning maneuver of the vehicle with a conventional torque-biasing system. During such maneuver, each of the four wheels of the vehicle track a different turning radius and, consequently, are turning at a different rotational speed. As an example, the number of tire tracks of a typical vehicle change from two tire tracks to four tire tracks as the vehicle turns into a snowy driveway. In this situation, the torque-biasing system may improperly interpret the different rotational speeds of the wheels as a reduced-traction situation and may improperly power all four wheels. In a tight turning situation, the powering of all four wheels causes a disturbing “crow hop” situation as the torque-biasing device attempts to reduce the rotational speed difference between the wheels of the vehicle, which must turn at a different rotational speed. Thus, there is a need in the field of torque-biasing systems to provide a torque-biasing system with an improved control algorithm and control unit.